ALDH2, the mitochondrial ALDH, has a very high affinity for acetaldehyde (KM = 0.2 μM) and a high reaction velocity (Vmax = 280/min) (Hurley et al., 2002, Klyosov, 1996) (Table 3). ALDH2 rapidly eliminates most of the acetaldehyde, unless it is inhibited by disulfiram or by an inactivating mutation (see below). In individuals with active ALDH2 enzyme, acetaldehyde in the bloodstream ranges from undetectable to about 3 μM, roughly 1000-fold less than the levels of ethanol (Mizoi et al., 1994, Peng et al., 2014a, Harada et al., 1983, Nuutinen et al., 1984). ALDH2 is expressed ubiquitously, with highest levels in liver and adipose (Figure 4); it is among the top 100 genes expressed in liver. No eQTLs affect its expression in liver.
